Producing unsaturated compounds



Patented Nov. 20, i945 UNlTED STATES PATENT OFFICE PRODUCING UNSATURATEDCOMPOUNDS Hans George Kirschenbauer, Allendale, N.-J., as-

signor to Colgate-Palmolive-Peet Company, Jersey City, N. J acorporation of Delaware No Drawing. Application July 22, 1942, SerialN0. 451,976

11 Claims.

that its drying properties are associated with the presence ofconstituents having a conjugated double bond structure. Other naturaloils, the polyunsaturated constituents of which have unconlugateddoublebonds, do not exhibit such fast-drying effect and in their naturalstate cannot be successfully substituted for tung oil,

It has been proposed to process these oils to improve their dryingproperties, and a recent patent describes a method for refluxing them inalcoholic solution with a basic reagent to convert constituents having'unconjugated double bonds to conjugated systems, The patented processemploys an amount of alcohol several times the weight of the oiltreated, and the refluxing operation is carried on over a period ofseveral hours. So far as is known, the art has not been able to developa method on a practical and industrial scale for successfully causingmigration of the double bonds to a conjugated position in a relativelyshort time and without the use of solvents.

It is an object of the present invention to provide an improved processfor causing the double bonds of polyunsaturated organic materials tobecome conjugated in a relatively short time.

It is also an object of the invention to provide a novel process forconvertingfatty oils, fatty acids and other fatty matter havingunconlugated double bonds into materials having conjugated double bondswithout the use of added solvents.

Other objects and advantages of this invention will be apparent from thefollowing description.

According to the present invention, materials containing organicaliphatic compounds having at least two double bonds in unconjugatedposition are treated, with or without additional fatty material, withsuitable alkaline agents and subjected in an inert atmosphere, andpreferably in the presence of excess alkali or other suitable catalyst,to a temperature above the melting point of the resulting anhydroussoaps. The treatment takes place in 9. closed vessel in the substantialalkaline or neutral catalysts.

absence of liquid water and of air or other oxidizing atmosphere, and aninert gas, such as steam, hydrocarbon vapor or nitrogen,'is preferablypassed through the molten reaction mixture.

Although the treatment may be carried out at superatmosph'eric pressure,at atmospheric pressure or under reduced pressure, it is preferred thata partial vacuum be applied. Glycerine, if any, and unsaponifiablematerial are vaporized by this treatment, and their removal from thereaction vessel is facilitated by the inert gas, where such gas isemployed. The vaporized material may be recovered, if desired.

The resulting mixture of anhydrous soap is drawn off in the fluid state,while taking suitable precautions to exclude harmful contact of air withthe hot soap. One way of accomplishing such withdrawal is to dischargethe fluid soap into and beneath the surface of a body of water oraqueous solution. The soap is dissolved in water to give an aqueoussolution thereof, and this solution is acidulated, preferably by theaddition of dilute mineral acid. The fatty acid can then be separatedout by decantation, withdrawal of the lower aqueous solution,centrifuging or the like, and may be subjected to fractionaldistillation, fractional crystallization and/or other separation andpurification procedures, if desired; The fatty acids may then beesterified with glycerine to produce an oil with fast-drying properties,or other esters may be formed by esterification with the correspondingalcohols.

Esterification of the free fatty acids with glycerine may beaccomplished by heating the mixture, preferably under vacuum, to about200 C. or higher, with or without the presence of a suitable catalyst,such as beta-naphthalene sulphonic acid, beta-camphor sulphonic acid, orother acid,

Care should be exercised in this operation, as excessive temperatures orlarge amounts of catalysts may cause polymerization of the unsaturatedacids. Glycerides may also be formed by first esterifying with a lowermonobasic alcohol, such as methyl alcohol, and then distilling theresulting ester with glycerine, with or without a catalyst, continuallyadding fresh glycerine and removing the alcohol as liberated. Anotherprocedure for producing glycerides is directly to react the anhydroussoap formed with 1,2,3-trichlor propane and to remove sodium chloridetherefrom.

Saturated and monounsaturated constituents of the oils may be separatedout in the form of their free fatty acids or esters, either before orafter treatment in accordance with the present process, by fractionaldistillation, fractional crystallization and/or solvent extraction, orother methods. However, the occurrence of some of the more saturatedmaterials as modifiers is sometimes of value in the product.

' The temperature of the treatment has been described supra as above themelting point of the resulting anhydrous soaps. Normally, while thistemperature is high enough to effect a desirable change in theproperties of the soap, migration of the double bonds to conjugatedpositions occurs at a somewhat higher temperature. In the usual case,such temperature will generally be of the orderof about 285 C. toabout'3l0 0., though temperatures up to about 350 C. or higher maysometimes be used, and in most cases temperatures of about 290 C. toabout 300 C. will be found suitable. The temperature limits arenecessarily set by the character of the resulting soap, as the migrationoccurs-at somewhat lower temperatures with some soaps. With respect tothe upper limit, the temperature above which substantial polymerizationor decomposition of the resulting soap occurs is not to be exceeded. Itis advantageous at all times to prevent local overheating anddecomposition at surfaces of contact between the reaction vessel and theproduct. During the treatment, the mass is thoroughly agitated, and theinert gas which is passed through the material may be employed as thesole or the supplementary means for such agitation, as well as forfacilitating the carrying off of volatilized material. Stirrers and/orother means for mechanically agitating the molten mass may also be usedto advantage.

The treatment of this invention is also applicable to materials whichare already in saponified form, and such saponified substances may betreated alone or with unsaponified fatty oils, esters and acids. Wherepart of the material subjected to the treatment is already saponified,it is advantageous during the initial stages of heating to prevent localoverheating and decomposition at the surface of contact between thereaction vessel and the product by first heating the saponified materialand maintaining it at a temperature of about 290 C. to about 300 C.where it is fluid, and then adding the unsaponified material at a ratenot substantially greater than the rate at which it may be heated to thetemperature necessary for fluidity. The process may be operated withcontinuous, intermittent, or batch additions of crude materials andwithdrawals of treated products.

An excess of caustic alkali is preferably employed, and, althoughvarious alkaline materials may be used for the saponiiication, freealkali in excess of the amount of alkaline material required forsaponification is added. Such excess of free alkali is preferablyequivalent to up to about 25% (usually more than about 0.5%) of thealkaline agent needed for saponifying the fatty material. The alkalinematerials which may be used include caustic alkalies like sodium orpotassium hydroxide, lime, carbonated alkalies like sodium or potassiumcarbonate, magnesium carbonate, etc., or mixtures thereof. If alkalinematerials other than caustic soda and soda ash are employed, it may benecessary or desirable to change thetemperatures used, because of thedifferences in the melting points of soaps formed with materials otherthan sodium. In any event, the temperature should be sufiiciently highto insure fluidity, being above the melting point of the resultinganhydrous soap and below the temperatu're of substantial decompositionor polymerization.

The following examples are merely illustrative of the present invention,and it will be understood that the invention is not limited thereto.

Example I phere above the reaction mass. The molten reaction mass isthen pumped from the vessel into about 300 parts of water, the reactionmass being admitted under the surface of the water to avoid oxidation. Asuflicient amount of dilute sulphuric acid for completely liberating themixture of fatty acids is added, and the aqueous mass is vigorouslyagitated. Upon settling, two layers are formed, and the lower aqueouslayer is withdrawn. The residue is washed with water to remove anyretained sulphuric acid from the fatty acids. The maleic anhydride valueof the product is determined, and a value of 24 is obtained, as comparedwith a maleic anhydride value of 2.5 for the original untreated linseedoil fatty acids. The acids produced thus give evidence of containing alarge proportion of constituents having conjugated dou-v ble bonds notpresent in the untreated acids, and glycerides formed therefrom exhibitfast-drying efiects.

Example II About 200 parts of cottonseed oil and about 33 parts ofpulverized'caustic soda are intermittently fed into a reaction vesselprovided with a mechanical stirrer, and the mixture is heated to about260 0. A stream of nitrogen is passed through the mass, and thetemperature of the reaction mass is rapidly raised to about 290 C. toabout 300 C. and held'at this temperature for about one hour. Duringthis time, the reaction mass is vigorously agitated with the aid of .thenitrogen stream, and glycerine and unsaponiflable and odoriferous matterare removed as vapors from the reaction chamber. The molten reactionmass is then pumped into a pressure mixing vessel, where it is dissolvedin water. The soap formed is acidulated, using dilute sulphuric acidtherefor,

V and, after .settling, the lower aqueous layer is Example III About 200parts of cottonseed oil and about 33 parts of pulverized caustic sodaare fed into a reaction vessel and subjected to the treatment of ExampleII, except that steam is passed through the mixture instead of nitrogen.The maleic an-.

hydride value of the fatty acids obtained in this manner is 11.8.

" maintained for about forty minutes.

bubbledthrough the molten mass throughout this aseaao treated esters andthe treated product are then .1

Example IV About 200 grams of menhaden oil are heated to about 275 C.,while a stream of steam is passed therethrough. About 45 grams ofcaustic potash are then added to the oil, a vacuum of about 26 virich'esof mercury is applied, and thetemperature is rapidly raised to about 288C. and there Steam is period, serving to agitate themixture, to providean inert atmosphere and to facilitate removal of glycerine andunsaponifiable matter. The soap formed is pumped into water containingsumcient hydrochloric acid to acidulate'th'e soap, and it is therevigorously agitated. The liquid mass settles into two layers, and theupper layer is de canted, washed and dried. The free fatty acids thusrecovered are mixed with glycerine anda small amount of beta-naphthalenesulphonic acid as an esterification catalyst, and the mixture is heatedunder partial vacuum at about 200 C. for about two hours to esterify.The glyceride formed is found to have a maleic anhydride value of 16and-to exhibit the properties of materials having conjugated doublebonds, including. fastdrying effects.

Emample V Cottonseed oil is alcoholized with methyl alcohol, and theresulting esters are distilled to remore a largeproportion of thepalmitic acid esters. A fraction having an iodine value of 121.5 and asaponification value of 19.17% potassium hydroxide is recovered andcontains most of the methyl oleate and methyl linoleate. A sample ofthis material is reserved without further treatment for subsequentcomparison. About 200 parts of the methyl esters are mixed with about 30parts of ground caustic soda and fed into a heated reaction vesselequipped with a mechanical agitator. Steam is passed through thereaction mass continuously, and the temperature is maintained at about250 C. throughout the feeding and is then rapidly raised to about 290 C.to about 300 C. and kept at this temperature range for about one hour,during which time the steam is continuously bubbled therethrough to aidin the agitation of the reaction mixture and to provide an inertatmosphere th'ereover. The reaction mass is thereafter run into water,and dilute sulphuric acid is added to the aqueous mass to acidulate thesoap. The material settles into two layers; the upper layer is siphonedoff, washed and dried and is then treated with about three to four timesits volume of methyl alcohol. A small amount of concentrated sulphuricacid is added as an esterifying agent, and the mass is refluxed forabout an hour. It is then permitted to stand in a warm place for abouttwenty-four hours, whereafter it is cooled, diluted'with water andextracted with ethyl ether. The ether extract is distilled to remove theether and to recover the methyl esters, and the esters are distilled ata pressure of about 2 mm. of mercury from a Claisen flask to separatethem from polymerized matter. About 85.5% distill below 200 C. and arerecovered.

The methyl esters distilling below 200 C. at 2 mm. of mercury pressureare then compared with the untreated methyl esters of the samplereserved for comparison, with reference to constituents of conjugateddouble bond structure. anhydride value of the esters of the treatedproduct is found to be 19.4, while the untreated esters have a maleicanhydride value of 0.9. Th unexamined with -a photoelectricspectrophotometer to determine their spectral extinction coefficients.spectrophotometry has become recognized as'a valuable means ofidentifying conjugated constitutents in the composition of fatty oils,esters, acids and the like, the conjugated due to the conjugation of themethyl linoleate' structures being characterized by intense absorptionbands, the location of which depends upon the nature of the specificchromoph'ore present in the molecule. A numerical comparison of theextinction coefflcient of an. unknown, such as the treated product inthe present example, with the extinction coefficient exhibited by areference compound, such as the untreated esters herein described, atthe same characteristic wave length is a measure of the increase incondugation effected. At about 2350 Angstrom units, the spectralextinction coefficient of the untreated esters is 6.3, while, at thesame wave length, the extinction coeflicient'of the product methylesters is 378. The increase .in the extinction coeflicient is doublebonds.

Among other materials containing-constituents having unconiugatedsystems. which may be treated by the present process are various naturaloils, includingcorn oil, soya bean oil, whaleoil, sardine and other fishoils.sesame seed oil, cottonseed foots, saillower seed oil, Perilla oil,sunflower oil, and the like, as well as fatty acids,

. esters and salts thereof. Materialscontaining smaller proportions ofunconjugated double bond constitutents, such as tallow, garbage greaseand the like and their derivatives, can also be treated by this processto cause migration of the double bonds of said'constituents intoconjugated positions, although it-is preferred to employ these materialsin admixture with materials containing 40 larger proportions ofconstituents having uncon- The maleic jugated double bonds. Varioussynthetic materials, including fatty acids having unconjugated doublebonds and prepared by dehydrohalogenation of polychlorinated saturatedacids or dehydration of hydroxy-unsaturated acids, such as ricinoleicacid, or the like, may also be treated by this process. I

Various fatty'materials and fatty acids may be employed inadmixture'with the fats and oils containing constituents havingunconjugated double bonds, and it is also possible to add other organicmaterials at any point during the process. For example, various oils,fats, waxes, and resins may be added to the reaction vessel, and theseinclude wool fat, spermaceti, various grades of wood and gum rosin,coconut oil, olive oil, palm oil, tung 0il,' oitic ica oil, montan wax,carnauba wax, Japanese wax and Chinese wax, as well as the variousindividual fatty or resin acids or derivatives thereof .or mixtures ofany of these fats, oils, waxes, resins and acids.

Besides their availability as a source of fastdrying oils, the productsof the process of the present invention containing constituents havingconjugated double bonds, with or without the addition of other fattymaterials, can be used for many other purposes. As will be apparent fromthe foregoing, they may be used in the synthesis of various organiccompounds, such as tricarboxylic acids. The free fatty acids may also bemixed with other acids, such as phthalic acid, maleic acid, succinicacid, abietic acid, etc., and the mixture esterified with glycerine orother polyhydric alcohols to form alkyd resins for use as bondingmaterials. These materials are generally more reactive in the conjugatedform, and, due to the migration of the double bond, diflerent carbonatoms are made availablefor additions.

The term "polyunsaturated" as applied to the raw materials and productsof the present process is intended to include materials having two ormore double bonds, whether conjugated or unconjugated.

Aithough the present invention has been de-- scribed with respect toparticular embodiments and examples thereof, it will be understood bythose skilled in the art that other variations and modifications of theinvention can be made and that various equivalents can besubstituted'therefor without departing from the principles disclosedherein. Such variations and modifications are believed to be within thescope of the present specification and within the purview of theappended claims.

Iclaim:

1. A process which comprises heating a polyunsaturated fatt materialhaving unconlugated double bonds with an amount of alkaline agent fromabout 1.005 to 1.25 times that required for saponification in an inertatmospher at a temperature within the range of about 285 C. to

about 350 C. but below the temperature of substantial polymerization of,the resulting anhydrous product while maintaining the heated mixture inmolten and substantially anhydrous condition, whereby a productcontaining polyunsaturated compounds having conjugated double bonds isformed, acidifying said product, recovering fatty acids from saidacidified product and esterifying said fatty acids with alcohol.-

2. A process which comprises heating at a pressure not substantially inexcess of atmospheric pressure a polyunsaturated fatty material havingunconlugated double bonds with an excess of alkaline agent notsubstantially greater than'25% of that required for saponification inthe absence of air at a temperature within therange of about 285 C. toabout 350 C. but below the temperature of substantial polymerization ofthe resulting anhydrous product while maintaining the heated mixture inmolten and substantially anhydrous condition and while thoroughlyagitating and intimately contacting the mixture with a stream of aninert gas, whereby a'product containing polyunsaturated compounds havingconjugated double bonds is formed, acidifying said product, recoveringfatty acids from said acidified product, and esterifying said fattyacids with alcohol 3. A process which comprises heating at substantiallyatmospheric pressure a polyunsaturated fatty material havingunconjugated double bonds with an alkaline agent in the'absence of airat a temperature of about 285 C. to about 310 C. but below thetemperature of substantial polymerization of the resulting anhydrousproduct while maintaining the heated mixture in molten and substantiallyanhydrous condition and while passing a current of steam through saidmixture, said alkaline agent comprising free alkali up to 25% excess ofthe amount of alkaline agent required to saponify said fatty material,whereby a product containing polyunsaturated compounds having conjugateddouble bonds is formed, acidifying the product, recovering fatty acidsfrom said acidified product, and esterifying said fatty acids withpolyhydric alcohol to produce a drying oil.

4. A process which comprises heating at substantially atmosphericpressure a polyunsaturated fatty material having unconiugated doublebonds 1.25 times. the amount required for saponifica- I with an alkalineagent in an amount from about 1.005 to 1.25 times that required forsaponiflcation in the absence of air at a. temperature of about 290C. toabout 300 C. while maintaining the heated mixture in molten andsubstantially anhydrous condition and while passing a current of steamthrough said mixture, whereby a product containing polyunsaturatedcompounds having coniugated double bonds is formed, acidifying saidproduct, recovering fatty acids from said acidified product, andesterifying said fatty acids with polyhydric alcohol, saidcsteriflcation being carried out in admixture with other carboxylicacids.

5. A process which comprises heating at a pressure not substantially inexcess of atmospheric pressure a fatty material selected from the groupconsisting of natural oils containing polyunsaturated constituentshaving unconjugated double bonds and acids, esters and soaps of saidoils with an excess of alkaline agent up to 1.25 times that required tosaponify the fatty material in the absence of air at a. temperaturewithin the range of about 285 C. to about 350 C.- but below the tem:perature of substantial polymerization of the resulting anhydrousproduct while maintaining the heated mixture in molten and substantiallyanhydrous condition and while thoroughly agitating and intimatelycontacting the material with a current of steam, whereby polyunsaturatedcompounds having conjugated double bonds are formed, and converting saidcompounds to polyhydric alcohol esters of thefatty acid radicalsthereof.

6. A process which comprises heating a fatty material selected from thegroup consisting of natural oils-containing polyunsaturated constituentshaving uncondugated double bonds and acids, esters and soaps of saidoils with an alkaline agent comprising excess free alkali up to abouttion under reduced pressure and in the absence of air at a temperatureof about 285 C. to about 310 C. but below the temperature of substantialpolymerization of the resulting anhydrou product while maintaining theheated mixture in molten and substantially anhydrous condition and whilethoroughly agitating and intimately contacting the mixture with a streamof an inert gas, whereby a product containing polyunsaturated com poundshaving conjugated double bonds is formed,

acidifying the product recovering fatty acids from said acidifiedproduct, and esterifying said fatty acids with glycerlne.

7. A process which comprise heating a fatty material selected from thegroup consisting of natural oils containing polyunsaturated constituentshaving unconjugated double bonds and acids, esters and soaps of saidoils with excess alkaline agent up to 1.25 times the amount required forsaponification in the absence of air at a temperature of about 290 C. toabout 300 C. while maintaining the heated mixture in molten andsubstantially anhydrous condition and while passing a current of steamthrough said mixture, whereby a product containing polyunsaturatedcompounds having conjugated double bond is formed, acidifying theproduct, recovering fatty acids from rated constituents havingunconjugated double bonds and acids, esters and soap of said oil with analkaline agent in the absence of air at a temperature within the rangeof about 285 C. to about 350 C. but below the temperature of substantialpolymerization of the resulting anhydrous product while maintaining theheated mixture in molten and substantially anhydrous con-' stantiallyatmospheric pressure a fatty material selected from the group consistingof natural oils containing polyunsaturated constituents havingunconjugated double bonds and acids, esters-and soaps of said oils withan alkaline agent in the absence of air at a temperature of about 285 C.to about 310 C. but below the temperature of substantial polymerizationof the resulting anhydrous product while maintaining the heated mixturein molten and substantially anhydrous condition and while passing acurrent of steam through said mixture, said alkaline agent comprising anexcess of free alkali equivalent to up to about 25% of the amount ofalkaline agent necessary not containing polyunsaturated compound; havingconjugated double bond is formed, acidifying the reaction product,recovering fatty acids from said product, and reacting said fatty acidswith polybasie carboxylic acids and polyhydric alcohol to form a resin.

10. A process which comprises heating at a pressure not substantiallyhigher than atmospheric pressure a soap of fish oil fatty acids with upto 25% excess of sodium hydroxid in the absence of air at a temperatureof about 285 0.120 about 300 C. while maintaining the heated mixture inmolten and substantially anhydrous condition and while passing a currentof steam therethrough, whereby a product containing polyunsaturatedcompounds having conjugated double bonds is formed, acidifying saidproduct, recovering fatty acids from said acidified product, andreacting said fatty acids with alcohol.

11. A process which comprises heating at a pressure not substantiallyhigher than atmospheric pressure a soap of linseed oil fatty acids withup to 25% exces of sodium hydroxide in the absence of air at atemperature of about 290 C. to about 300 C. while maintaining the heatedmixture in molten and substantially anhydrous condition and whilepassing. a current of steam therethrough, whereby a product containingpolyunsaturated compounds having conjugated double bonds is formed,acidifying said product, recovering fatty acids from said product, and

esterifying said fatty acids with polyhydric alcoto saponify said fattymaterial, whereby a prod hol to form a drying oil.

HANS GEORGE HENBAUER.

